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    • Vishnu Procede N54 misfire mystery solved? CPS offsetting to blame?


      With all the discussion on the CPS offsetting lately, I have been delving deeper into this topic and contacting various tuners to get to the bottom of it. Now, we all know the Procede has had and still has misfire problems and the JB has not had this problem. As I have learned more about the impact of this system I have spoken to a couple tuners who pointed me in the right direction.

      What is the major difference between the two? CPS offsetting.

      Why would CPS offsetting cause misfires? Well, if the CPS offsetting is based on load and not static it will wreak havoc with the misfire detection of the DME. Here is how the Procede does CPS offsetting:

      So, the more load the more offset. Why is this a problem? The ECU uses the CPS signal to mesaure the acceleration of the crankshaft. If the acceleration value is outside what the DME expects, it is interpreted as a misfire. So when the ECU goes to measure the crank speed and this signal is changed, boom, misfire.

      Why has this been difficult to pin down? Because the Procede varies the offset and it isn't static. CPS offsetting isn't the right way to reduce ignition timing but the only option the Procede really has, as do all N54 piggybacks. Since the number isn't static misfires will happen based on a ton of variables that affect the ECU, load, weather, rpm, VANOS, etc. This is why there is no rhyme or reason to it only the constant of CPS offset.

      Further evidence that supports this theory is that Terry of BMS has recently been doing CPS Offset Testing and has been able to induce misfires with the CPS offsetting. So, hopefully this clears things up for people and to be noted a static offset may be best to prevent misfires. Ideally though, tuners we have contacted stated they believe such a vital part of the way the factory DME functions should not be messed with due to its impact on VANOS and the knock detection system.

      This article was originally published in forum thread: Procede misfire mystery solved? CPS offsetting to blame? started by Sticky View original post
      Comments 188 Comments
      1. alpinedevil335's Avatar
        alpinedevil335 -
        Can we get an adult/mature type comment from Shiv?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by alpinedevil335 Click here to enlarge
        Can we get an adult/mature type comment from Shiv?
        He is free to refute or address anything posted.
      1. alpinedevil335's Avatar
        alpinedevil335 -
        Poor choice of words....I meant "will" we?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by alpinedevil335 Click here to enlarge
        Poor choice of words....I meant "will" we?
        Ah, I doubt it due to this all being correct and that it can not be spun or removed. We will interpret lack of response as confirmation since the parties in question have already read the thread.
      1. alpinedevil335's Avatar
        alpinedevil335 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Ah, I doubt it due to this all being correct and that it can not be spun or removed. We will interpret lack of response as confirmation since the parties in question have already read the thread.
        Yes we will.
      1. shiv@vishnu's Avatar
        shiv@vishnu -
        lol... wrong. The theoretical compression stroke in a 4 cycle internal combustion engine is 180deg. But with real-world valve timing dynamics, it's closer to 145 degrees. Of course, this will vary from engine to engine.

        Static vs. dynamic CPS offsetting isn't the key to avoiding misfire diagnostics. Our CPS offsetting is more dynamic now than it's ever been and we are supporting up to the limits of the factory ignition system misfire-free Click here to enlarge
      1. Forcefed's Avatar
        Forcefed -
        So if the guys at vishnu know more about controlling timing than BMW, why dont they just make their own car?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        The theoretical compression stroke in a 4 cycle internal combustion engine is 180deg. But with real-world valve timing dynamics, it's closer to 145 degrees. Of course, this will vary from engine to engine.
        What is the adjustment window? Is it 180 degrees? 145 degrees? Forget the compression stroke, how many degrees of adjustment do you have?

        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        Static vs. dynamic CPS offsetting isn't the key to avoiding misfire diagnostics. Our CPS offsetting is more dynamic now than it's ever been and we are supporting up to the limits of the factory ignition system misfire-free
        What are the limits of the factory ignition system?

        Thank you for confirming the CPS offset / misfire connection and I hope your new offsetting (not sure how it differs) solves any issues.
      1. shiv@vishnu's Avatar
        shiv@vishnu -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        What is the adjustment window? Is it 180 degrees? 145 degrees? Forget the compression stroke, how many degrees of adjustment do you have?
        The adjustment range is +/- 15 degrees.

        What are the limits of the factory ignition system?
        Oh right around 500whp, you will run into high rpm misfire from time to time.

        Thank you for confirming the CPS offset / misfire issues and I hope your new offsetting (not sure how it differs) solves any issues.
        It wasn't the offset that caused the misfire. For those cars that misfired, even running an offset of 0 deg (no offset) resulted in misfire. So there goes your theory, huh?

        Shiv
      1. Terry@BMS's Avatar
        Terry@BMS -
        I still want to know how bad your CPS resolution had to have been all these years to suddenly be able to improve it 800%. It sounds like that was the mistake all along...
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        It wasn't the offset that caused the misfire. For those cars that misfired, even running an offset of 0 deg (no offset) resulted in misfire. So there goes your theory, huh?
        No, because you haven't proved that is the case and it would not be beyond you to simply say so in order to save face.

        If anything, the correlation between the CPS offset and misfiring has been strengthened. How else do you explain JB's without CPS not having this problem? What proof do you have? Haven't cars that have changed hardware still had misfire problems after the change? Isn't the constant the tune? So...

        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        The adjustment range is +/- 15 degrees.
        How much of this range is it that you use?
      1. mazdaspeed6's Avatar
        mazdaspeed6 -
        Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
        I still want to know how bad your CPS resolution had to have been all these years to suddenly be able to improve it 800%. It sounds like that was the mistake all along...
        Lmfao I was thinking the same thing when I read that
      1. Terry@BMS's Avatar
        Terry@BMS -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        No, because you haven't proved that is the case and it would not be beyond you to simply say so in order to save face.

        If anything, the correlation between the CPS offset and misfiring has been strengthened. How else do you explain JB's without CPS not having this problem? What proof do you have? Haven't cars that have changed hardware still had misfire problems after the change? Isn't the constant the tune? So...
        I think their new claim is that Adrian Vos made a programming mistake and was not catching/updating edges with enough precision to avoid a false misfire detection. The problem with a troubleshooting misfire code is you have many possible causes all giving the same symptom.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        Oh right around 500whp, you will run into high rpm misfire from time to time.
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        It wasn't the offset that caused the misfire. For those cars that misfired, even running an offset of 0 deg (no offset) resulted in misfire. So there goes your theory, huh? Shiv
        maybe on your cars Click here to enlarge so maybe that DOES support his theory Click here to enlarge


        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        If anything, the correlation between the CPS offset and misfiring has been strengthened. How else do you explain JB's without CPS not having this problem? What proof do you have? Haven't cars that have changed hardware still had misfire problems after the change? Isn't the constant the tune? So...
        I seem to recall another 500hp range car dyno'ing the same time frame as his, but no CPS offset, and did NOT have a misfire,even going ALL......THE..........WAY............THROUGH...... .....REDLINE...............
        Cheers,

        LM
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by mazdaspeed6 Click here to enlarge
        Lmfao I was thinking the same thing when I read that
        I don't want this to be a "let's everyone piss on Shiv" thread. I know that isn't what you are doing but I just want to point out unlike the other threads I want to maintain this one as being constructive since Shiv is taking a civil tone (for now).
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        I seem to recall another 500hp range car dyno'ing the same time frame as his, but no CPS offset, and did NOT have a misfire,even going ALL......THE..........WAY............THROUGH...... .....REDLINE...............
        Cheers,
        This is true, 500 whp through the entire powerband and no misfires.

        My belief and that of some other tuners is that this is all CPS related. Terry has induced misfires by messing with the CPS. I believe the connection is clear due to how what offsetting does the ECU.
      1. shiv@vishnu's Avatar
        shiv@vishnu -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        This is true, 500 whp through the entire powerband and no misfires.

        My belief and that of some other tuners is that this is all CPS related. Terry has induced misfires by messing with the CPS. I believe the connection is clear due to how what offsetting does the ECU.
        Ask Ultimateracing335 about his top end misfire when he was running the jb4. No CPS offsetting there. And a bit shy of 500whp. On the dyno and on the road.

        Shiv
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        Ask Ultimateracing335 about his top end misfire running the jb4. No CPS offsetting there. And a bit shy of 500whp.

        Shiv
        so was his 511 and other 5xx runs with v5 or with jb4? because i have plenty of questions about those runs..
      1. shiv@vishnu's Avatar
        shiv@vishnu -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        so was his 511 and other 5xx runs with v5 or with jb4?
        v5. I don't believe he ever broke 500whp with the jb.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by shiv@vishnu Click here to enlarge
        v5. I don't believe he ever broke 500whp with the jb.
        so, after i just uploaded them to the dyno thread, i noticed that it looks like he was having some major issues with those runs.. couldnt rap it out past 6200 rpm, and the ones that did.. uh.. looked like something was going on.. care to elaborate?

        http://www.bimmerboost.com/showthrea...ilation-Dyno-s